1. Field of the Invention
This invention relates to electromagnetic relays, and more particularly to high-speed, high-reliability electromagnetic relays particularly adapted for use in DC power and high-frequency electronic systems.
2. Description of Related Art
Despite the advances of all-electronic switching devices, in many applications, electromagnetic relays are still necessary. This is particularly true in applications that subject electronic circuitry to vibration, high shock, high acceleration, and widely varying environmental temperature and humidity conditions.
Electromagnetic relays suitable for such applications have in the past typically been internally complex, and therefore expensive to manufacture. One such typical prior art relay, manufactured by the Teledyne Corporation as its model 412K Series TO-5 Relay, includes a metallic rocker armature having a small push spring with an insulating glass bead to push a reed contact from a first position to a second position when the electromagnetic force attracts the armature, and a larger push spring to return the rocker to its first position when the electromagnet is deactivated. Fixed at one end, the flat reed functions as the larger push spring. The reed must be adjusted to the proper resilience to provide the force to return the rocker to its first position. Because of this requirement, there is a limit to the reed thickness and hence its current carrying capacity. Other disadvantages of this type of design include a relatively high number of moving parts, welded joints which can fail, the presence of springs that must be adjusted to the proper resilience during manufacture to provide repeatable performance specifications and which can suffer metal fatigue over time, and a frequency limit for transmitted signals of about 500 MHz. The reason for the frequency limit is the open construction of the contacts, which thus lack RF shielding.
The present invention is designed to overcome these disadvantages, and provide an electromagnetic relay that is highly reliable, simple in construction, relatively inexpensive to manufacture, able to meet the environmental standards typically required in applications employing such relays, and which can handle transmitted signals from DC to about 8 GHz.